Silicon carbide MEMS temperature-pressure composite sensor chip and preparation method thereof

Abstract

The invention discloses a silicon carbide MEMS temperature and pressure composite sensor chip and a preparation method thereof. The sensor chip comprises a peripheral pressure measuring unit and a central temperature measuring unit; the pressure measuring unit comprises a silicon carbide substrate with a convex island, and a circular back cavity is etched on the back surface to form a pressure sensitive diaphragm; wherein the convex islands and the pressure sensitive membrane form a membrane island structure; four piezoresistive strips are symmetrically arranged outside the convex island and inside the pressure sensitive diaphragm along the circumference of the root of the pressure sensitive diaphragm; the temperature measuring unit comprises a substrate convex island and a thin film thermocouple arranged on the substrate convex island; When pressure acts on the chip, the pressure measuring unit converts the pressure into an electric signal through a semiconductor piezoresistive effect and a Wheatstone bridge and outputs the electric signal. Meanwhile, the temperature measuring unit converts the temperature into thermoelectric force through the Seebeck effect of a metal film thermocouple and outputs the thermoelectric force, so that real-time detection of the pressure and the temperature at the high temperature is completed. The sensor chip has the advantages of high temperature resistance, miniaturization, high sensitivity, good stability and the like.

Description

technical field [0001] The invention belongs to the technical field of MEMS sensors, and in particular relates to a silicon carbide MEMS temperature-pressure composite sensor chip and a preparation method thereof. Background technique [0002] In aerospace, geothermal development, gas turbine and other fields, higher requirements are put forward for the measurement of high temperature environment pressure and temperature, especially in the combustion chamber of aeroengine and gas turbine, real-time measurement of pressure and temperature is very important for monitoring engine performance, improving combustion efficiency, Designing and improving next-generation engines is critical. At present, the common measurement of pressure and temperature under high temperature is to use high temperature resistant pressure sensor and temperature sensor to measure separately. The chip manufacturing cost is high, the sensor installation space is large, and the lead wire is complicated. A...

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Problems solved by technology

At present, the common measurement of pressure and temperature under high temperature is to use high temperature resistant pressure sensor and temperature sensor to measure separately. The chip manufacturing cost is high, the sensor installation space is large, and the lead is complicated.

And due to the limitations of material properties, the current mainstream silicon-based pressure sensors generally do not exceed 300°C in temperature. For combustion chamber environments where the temperature generally exceeds 500°C, an additional cooling device is required to use them.

With the development of MEMS technology, temperature and pressure integrated sensors have begun to appear, but they are basically divided into two units on one chip to measure temperature and pressure respectively. The utilization rate of chip space is not high, and it is limited by the properties of silicon-based materials. At present, the pressure sensor is not suitable for high temperature

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